According to Superhero Hype, Immortals and Xerxes producer Mark Canton, stated that Xerxes may not be able to wait for Snyder to complete his work on the new Supes flick:

“I can’t say…I mean, he’s got ‘Superman.’ He’s busy. We’re busy. I don’t think we’re going to wait two years. But we’ll work together with him and figure out who the filmmaker should be if he doesn’t direct it.”

“We’re taking a lot of time because [Zack] really did create something that goes in the time capsule… We want to be faithful to the first one, but we don’t want to do a conventional sequel. But we’re getting close.”

Sigh. I guess my hopes that we were all going to dodge this bullet just went up in smoke, huh? Oh, well, if there’s one thing the world needs, it’s a CGI-laden violence extravaganza that hijacks historical characters in order for 18-24 males can zone out for two hours.